Apparatus for the production of blocks from sodium hydroxide solution

ABSTRACT

Solid blocks are formed from sodium hydroxide solution by supplying molten lye by gravity feeding to a vertical cooling shaft and cooling the solution from above in repeated incremental steps while ejecting the solidified extrusion from the shaft downwardly. The cooling and the ejection are carried out by the displaceable downward movement of cooling elements. After each cooling step, the elements are retracted and the shaft is filled up to the original level with the sodium hydroxide solution. During each subsequent step at least a portion of the refill melt present between the solidified extrusion and the cooling elements is solidified by cooling. The apparatus advantageously includes a vertically elongated cooling tower having cutting means associated with the lower end thereof for cutting the extrusion which is ejected through the lower end in desired block size lengths. The cooling elements advantageously comprise one or more fixed cooling elements and one or more elements which move into and out of the tank from above. The elements are tapered conically downwardly in order to facilitate the separation of the elements from the solidified material after it is formed. The shaft is provided with cooling coils adjacent the upper end thereof for aiding in the solidification and also with heating coils directly adjacent the top of the shaft in order to maintain a melted condition or a controlled melted or solid condition in accordance with preferred operating procedures.

Kiihnlein [54] APPARATUS FOR THE PRODUCTION OF BLOCKS FROM SODIUM HYDROXIDE SOLUTION [75] Inventor: Hans Kiihnlein, Fullinsdorf, Switzerland [73] Assignee: Hch. Bertrams Aktiengesellschaft, Basel, Switzerland [22] Filed: Nov. 27, 1970 [21] Appl. No.: 93,165

[52] US. Cl. ..425/224, 164/82, 164/283, 264/212, 425/307 [51] Int. Cl. ..B22d 11/10, B22d 11/12 [58] Field of Search ..18/26 R, 39; 164/260, 281, 164/282, 283; 264/212, 332

[56] References Cited UNITED STATES PATENTS 2,517,001 8/1950 Lewon et al. ..l8/26 R X 3,068,513 12/1962 Chaffin ..18/26 R UX 3,143,413 8/1964 Krapf ..264/332 UR 3,344,846 10/1967 Rossing ..l64/28l 3,390,716 7/1968 Rossing....

3,658,116 4/1972 Hunt ..164/283 X FOREIGN PATENTS OR APPLICATIONS 1,201,955 9/1965 Germany ..l64/260 1,136,453 9/1962 Germany ..164/281 Primary Examiner-R. Spencer Anncar Attorney-McGlew and Toren [57] ABSTRACT Solid blocks are formed from sodium hydroxide solution by supplying molten lye by gravity feeding to'a vertical cooling shaft and cooling the solution from above in repeated incremental steps while ejecting the solidified extrusion from the shaft downwardly. The cooling and the ejection are carried out by the displaceable downward movement of cooling elements. After each cooling step, the elements are retracted and the shaft is filled up to the original level with the sodium hydroxide solution. During each subsequent step at least a portion of the refill melt present between the solidified extrusion and the cooling elements is solidified by cooling. The apparatus advantageously includes a vertically elongated cooling tower having cutting means associated with the lower end thereof for cutting the extrusion which is ejected through the lower end in desired block size lengths. The cooling elements advantageously comprise one or more fixed cooling elements and one or more elements which move into and out of the tank from above. The elements are tapered conically downwardly in order to facilitate the separation of the elements from the solidified material after it is formed. The shaft is provided with cooling coils adjacent the upper end thereof for aiding in the solidification and also with heating coils directly adjacent the top of the shaft in order to maintain a melted condition or a controlled melted or solid condition in accordance with preferred operating procedures.

PATENTEDJMI, 91ers 3. 709,648

INV ENTOR. Hans Kuhnlenn \MQ Q MITM APPARATUS FOR THE PRODUCTION OF BLOCKS FROM SODIUM IIYDROXIDE SOLUTION SUMMARY OF THE INVENTION This invention relates in general to apparatus for producing solid blocks from sodium hydroxide solution and in particular to a new and useful apparatus wherein a solution of sodium hydroxide is fed to a shaft and is cooled at the top of the shaft as the previously solidified hydroxide is moved downwardly directly after it is formed, and is subsequently cut into blocks as it exits from the shaft.

Sodium hydroxide or lye in crystalline form is a commercial product. The flakes, pellets or grains of the sodium hydroxide which are frequently produced require a relatively large and expensive packing because of the relatively large bulk weight of about 1 kg/ltr, and they also render transportation difficult. In a known method, a molten lye is filled in barrels which serve after the solidification of the lye as a packing therefore. The usual round barrels, however, also require relatively much transportation space and are heavy and expensive besides. In order to avoid these disadvantages a continuous method has been proposed where the liquid lye is forced through a prismatic horizontal shaping and cooling shaft. The solid lye extrusion which leaves the shaft is subsequently cut up into individual blocks. Since with this method, only a circumferential portion of the wall of the shaft is available for cooling, it is necessary, because of the poor heat transfer of the crystalizing lye, to make the shaft cross section relatively small and this leads to correspondingly small block dimensions. If additionally, cooling ribs engaging into the solid lye formation and forming grooves in the same are provided on the shaft wall, this, of course, results in a better cooling of the formation core but it necessarily leads to a worse weight volume ratio of the finished blocks. In addition, it increases the friction of the formation in the shaft to such an extent that pressure heads of over 60 atmospheres excess pressure would be required to be able to push the lye solidifying in the shaft through the shaft. The absence of economical delivery pumps for such high pressures and which will withstand the aggressive lye in permanent operation makes this method virtually impractical.

In accordance with the invention, the disadvantages of the prior art are avoided. With the invention, the molten lye is supplied by gravity to a vertical cooling shaft and it is cooled successively from above by directing cooling elements downwardly into the shaft for cooling the liquid lye as it is supplied in each successive step. The elements are moved downwardly sufficiently to cause the ejection of the solidified extrusion from the lower end of the shaft during each cooling step movement. After each extraction of the cooling elements the shaft is again filled up to the original level by gravity infeed and at least a portion of the refill liquid melt which is present between the solidified extrusion and the cooling elements is solidified by the next cooling step in which the elements are again moved downwardly into the tower.

The filling or refilling of the vertical shaft by gravity permits elimination of the trouble prone pressure pump. The dead weight of the extrusion which solidi fies in the shaft also contributes to each ejection. The ejection steps and hence the quantity of refill melt which will be solidified during each step by the cooling during each working stay or cycle can be selected so small that, in particular owing to the cooling elements acting from above, rapid solidification of the refill melt is attained, even at large shaft cross sections. A large shaft cross section means a large extrusion cross section so that relatively large blocks weighing for example, 50 kg can be produced.

The inventive apparatus advantageously includes a solidifying tower or shaft having means at the upper end thereof for cooling the wall around the circumference and also having means at the top for heating this portion of the top to maintain a liquid condition in the event that it is necessary for the movement operation of the cooling elements. The cooling elements themselves comprise one or more fixed elements and/or one or more movable elements which may be moved into and out of the top during each cooling cycle of operation. The individual cooling elements are tapered downwardly to a point to facilitate the downward movement of the extrusion which is formed and the lower end of the shaft carries cutting means for severing the solid material which is moved out of the shaft and after it is accumulated to a desired block size.

Accordingly, it is an object of the invention to provide an improved apparatus for forming solid blocks of lye from a liquid melt of the lye and using one or more movable cooling elements and a cooling shaft comprising cooling a quantity of the liquid lye by contacting the lye from above its surface with the cooling elements to solidify the liquid lye and to direct the solidified lye downwardly immediately after it is frozen, and repeating the movement of the cooling elements first out of the association with the solid lye to leave a space for the inflow of additional liquid lye and then downwardly into association with the fresh liquid lye to solidify it and direct it downwardly until a quantity of the solidified lye is accumulated below the lower end of the shaft and thereafter cutting the accumulated solidified lye into blocks.

A further object of the invention is to provide apparatus for solidifying liquid lye which uses a vertically elongated tower or shaft opened at the top and the bottom and having a means for feeding liquid lye by gravity into the top thereof and using one or more movable cooling members, comprising means directing the cooling members downwardly into the tower from above to cool a quantity of the liquid lye therein and subsequently pushing the solidified lye downwardly so as to cause the eventual outward movement of the lye from the bottom of the tower, means withdrawing the cooling member and permitting the liquid lye to feed by gravity into the tower above the solid lye to a predetermined height level, and means thereafter again advancing the cooling member into association with the liquid lye to freeze it and to move the newly frozen lye and the already solid lye downwardly in the tower.

A further object of the invention is to provide a device for solidifying liquid sodium hydroxide into solid blocks which comprises a vertically elongated tower open at the top and the bottom and which is located below means for moving cooling elements into and out of the top, and including means for feeding liquid sodium hydroxide to the top, said movable cooling elements being movable downwardly to engage the liquid sodium hydroxide and solidify it and move the solidified hydroxide downwardly so as to eventually to cause it to project out from the bottom of the tower, and means associated with the bottom for cutting the solidified hydroxide into a block.

A further object of the invention is to provide a device for solidifying hydroxide which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustraded a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a partial vertical section of a device for solidifying sodium hydroxide constructed in accordance with the invention;

FIG. 2 is a section similar to FIG. 1 but rotated 90 in relation to FIG. 1; and

FIG. 3 is a section taken on the line IIIIII of FIG. 1.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in particular, the invention embodied therein comprises a vertical shaft or tower' generally designated 1 which is in the form of a flat cylinder and which is open at the top and the bottom or at both ends in the event that the shaft is arranged horizontally.

The shaft 1 includes a hollow jacket or cooling medium flow space 2 adjacent the upper end for aiding in the cooling and solidifying of the sodium hydroxide. Above the cooling jacket 2 and directly adjacent the top of the shaft 1 are a plurality of coils 5 which provide means for heating this area of the shaft.

In accordance with a feature of the invention liquid lye is supplied from a lye tank 4 through a gravity feed line 3 to the upper portion of the shaft 1. The lye feeds downwardly through the line 3 to fill the shaft 1 to a predetermined level of operation during each cooling step.

The lower end of the shaft 1 is provided with cutting means in the form of a severing device or a double knife 6 as shown in FIG. 2. The lower end of the shaft 1 is arranged above a curved guide plate 7 which has a lower end oriented directly adjacent a roller conveyor 8 so that the severed solid blocks 14 oflye are delivered from the shaft 1 through a curved guide and onto the conveyor 8.

Cooling means are associated with the top of the shaft 1 and include a plurality of laterally spaced fixed cooling elements 12b and a plurality of movable cool ing elements 12a alternately arranged with the fixed elements. The movable elements 12a are carried on a traverse or cross beam 11 which is secured to a piston rod a of a piston 10 which is movable in a fluid cylinder 19 located in a fixed position above the shaft l. The fluid cylinder 19 and piston 10 combination comprises pusher means 9. The movable piston 10 comprises a pushing device to cyclically shift the movable cooling elements 12a from the solid line position indicated upwardly to the dotted line position of the cross member 11 shown in FIG. 1 and then back downwardly again for the next cycle of operation. All of the cooling elements 12a and the cooling elements 12b are tapered downwardly toward a point and are formed as individual conical members in order to facilitate their engagement and disengagement from the solid lye material which is formed during the operation. Depending on the size of the shaft cross section two or more rows of movable cooling elements 12a and 12b are provided. The hollow cooling elements 12a and 12b are connected with a cooling medium lines 15a and 15b, respectively which supply the cooling medium thereto. As the cooling medium for the jacket 2 and for the elements 12a and 12b ordinary water may be used for example.

Method of Operation:

When the device is to be operated for the first time, the shaft 1 must be temporarily closed at the bottom and the molten sodium hydroxide supplied from the tank 4 to feed by gravity up to the filling level indicated at the top. Since not only the layers of the melt or liquid sodium hydroxide which fill close to the walls are cooled but also due to the cooling elements immersed in the liquid melt the core portions of the filling are also cooled, the melt will solidify after a short period of time. After the movable elements 12a first contact the portion of the melt which is still liquid at the top it solidifies this portion and upon continued downward movement causes the whole lowermost solidified portion to be moved downwardly in the shaft as indicated at 13.

The pushing means 9 are operated to alternately raise and lower the cooling elements 12a. They are raised by relatively small amount for example a few cm and the fixed cooling elements 12b prevent the solidified lye from moving upwardly therewith. Solidification of the uppermost layer of lye in the shaft 1 is prevented by heating coil 5 which surrounds the upper shaft portion.

During the lifting portion of the cycle when the individual elements 12a are moved upwardly, there is an annular layer of conical form which is emptied as indicated by the dotted line shown in FIG. 1 and this is immediately filled up with the liquid at the top of the shaft 1. This melt which flows into this annular gap forms only a thin layer around the cooling elements and as these elements are brought into contact therewith it is immediately solidified.

With the solidified lye present around each of the elements there is again a downward movement of the movable elements 12a, but in so doing the lye is detached from the fixed cooling elements 12b and moved downwardly with the remainder 13 in the shaft 1. The displacement of the solid part 13 from the remainder forms an immediate gap around the fixed elements 121: which is immediately filled with additional liquid which is replenished by the gravity feed from the tank 4. Once again, the cooling elements 12a are lifted to form gaps which can be filled with a liquid sodium hydroxide and hence they are moved downwardly to advance the solid lye l3 downwardly in the shaft and this continues in repeated succession. The lye extrusion or solid material 13 which continuously increases from the lower end of the shaft 1 step by step. When a sufficient quantity of the lye 13 passes the severing device 6, it is cut up into a single block 14 of the desired length and this block falls on the guide plate 7 which deflects it onto the conveyor 8. From the conveyor 8 it is fed to a packaging station (not shown) where the blocks are packed, for example, in plastic foils.

The described device is simple in construction and operation. Despite the division of the process into several individual steps the continuous block production method is obtained. High pressure pumps and their associated valves and packings are not required. With such an installation it is possible to obtain block-forms and block sizes most favorable for transportation and handling weighing for example 50 kg and more, in dependence on the form and size of the shaft cross section and the number and arrangement of the cooling elements which are immersed in the shaft from above. The cooling time in the individual cooling step depends only on the selected lifting or lowering path of the cooling elements, that is, on the size of the particular annular gaps produced and not on the size of the block or shaft cross section. The heat transfer paths from the melt to the cooling face can be maintained correspondingly small.

I claim:

1. A device, for forming a liquid such as sodium hydroxide into a solid, comprising a shaft having a top end with an opening and a bottom end with an opening, at least one movable cooling member mounted adjacent said top end, means for adding the liquid to said shaft to maintain it at a predetermined level, means for moving the cooling member in a direction toward the bottom end to engage the liquid in the shaft and to cool the liquid to form it into a solid and to subsequently advance the solid form toward the bottom end, means to withdraw the cooling member in a direction away from the bottom end to form a gap, between the cooling member and the solid, which is filled by the liquid, and to cause cooling of the liquid as it moves into contact with said cooling member and to subsequently advance the cooling member to move the solid forwardly to said bottom end, and at least one fixed cooling member arranged in said shaft adjacent said top end, said movable cooling member being movable alongside said fixed cooling member and said fixed cooling member holding the solidified material against movement when the movable cooling member moves away from said bottom end.

2. A device, for forming a liquid such as sodium hydroxide into a solid, comprising a shaft having a top end with an opening and a bottom end with an opening, at least one movable cooling member mounted adjacent said top end, means for adding the liquid to said shaft to maintain it at a predetermined level, means for moving the cooling member in a direction toward the bottom end to engage the liquid in the shaft and to cool the liquid to form it into a solid and to subsequently advance the solid form toward the bottom end, means to withdraw the cooling member in a direction away from the bottom end to form a gap between the cooling member and the solld, Wl'llCll lS filled by the liquid, an

to cause cooling of the liquid as it moves into contact with said cooling member and to subsequently advance the cooling member to move the solid forwardly to said bottom end, there being a plurality of movable cooling members and a plurality of fixed cooling members arranged alternately across said top open end of said shaft, said cooling members being tapered downwardly to a point.

3. A device, for forming a liquid such as sodium hydroxide into a solid, comprising a shaft having a top end with an opening and a bottom end with an opening, at least one movable cooling member mounted adjacent said top end, means for adding the liquid to said shaft to maintain it at a predetermined level, means for moving the cooling member in a direction toward the bottom end to engage the liquid in the shaft and to cool the liquid to form it into a solid and to subsequently advance the solid form toward the bottom end, means to withdraw the cooling member in a direction away from the bottom end to form a gap, between the cooling member and the solid, which is filled by the liquid, and to cause cooling of the liquid as it moves into contact with said cooling member and to subsequently advance the cooling member to move the solid forwardly to said bottom end, cooling means adjacent the exterior of said shaft for cooling said top end, said cooling member comprising at least two fixed cooling members and at least three movable cooling members arranged alternately with said fixed cooling members, and cutting means at said bottom end for cutting the solid material which is formed in said shaft after it leaves said bottom end. 

2. A device, for forming a liquid such as sodium hydroxide into a solid, comprising a shaft having a top end with an opening and a bottom end with an opening, at least one movable cooling member mounted adjacent said top end, means for adding the liquid to said shaft to maintain it at a predetermined level, means for moving the cooling member in a direction toward the bottom end to engage the liquid in the shaft and to cool the liquid to form it into a solid and to subsequently advance the solid form toward the bottom end, means to withdraw the cooling member in a direction away from the bottom end to form a gap, between the cooling member and the solid, which is filled by the liquid, and to cause cooling of the liquid as it moves into contact with said cooling member and to subsequently advance the cooling member to move the solid forwardly to said bottom end, there being a plurality of movable cooling members and a plurality of fixed cooling members arranged alternately across said top open end of said shaft, said cooling members being tapered downwardly to a point.
 3. A device, for forming a liquid such as sodium hydroxide into a solid, comprising a shaft having a top end with an opening and a bottom end with an opening, at least one movable cooling member mounted adjacent said top end, means for adding the liquid to said shaft to maintain it at a predetermined level, means for moving the cooling member in a direction toward the bottom end to engage the liquid in the shaft and to cool the liquid to form it into a solid and to subsequently advance the solid form toward the bottom end, means to withdraw the cooling member in a direction away from the bottom end to form a gap, between the cooling member and the solid, which is filled by the liquid, and to cause cooling of the liquid as it moves into contact with said cooling member and to subsequently advance the cooling Member to move the solid forwardly to said bottom end, cooling means adjacent the exterior of said shaft for cooling said top end, said cooling member comprising at least two fixed cooling members and at least three movable cooling members arranged alternately with said fixed cooling members, and cutting means at said bottom end for cutting the solid material which is formed in said shaft after it leaves said bottom end. 